Performance Of DC Research Articles

A Hybrid Optimization Strategy for Minimizing Conversion Losses in Semi-Series-Resonant Dual-Active-Bridge Converter

To enhance the performance of resonant DC–DC converters, particularly under low-load conditions, a semi-series-resonant dual-active-bridge (Semi-SRDAB) converter with a hybrid optimization strategy is proposed. This strategy aims to reduce conduction-related losses and is designed for applications requiring a wide voltage range. The proposed Semi-SRDAB converter comprises a full-bridge inverter on the primary side and a hybrid-output bridge rectifier on the secondary side. It adopts phase-shift modulation combined with frequency modulation for power control. The hybrid optimization strategy for the Semi-SRDAB converter is investigated, beginning with the deduction of resonant current minimization using phasor analysis. Based on these analysis results, zero reactive power operation and soft-switching operation are achieved for both buck and boost modes. Successful validation has been demonstrated through experimental testing on a 300 W laboratory prototype. Enhanced conversion performance is confirmed by comparing the results with those from previous works.

Efficient voltage control strategy: observability design for multistage DC–DC buck converter

This paper emphasizes the significance of implementing an effective control system to enhance the performance of a three-stage DC–DC buck converter (TDDC). Herein, we present the development of an observer controller (OC) for TDDC, where average modeling of the DC–DC converter was employed alongside an observer algorithm for the OC. The primary focus is on the adoption of an observation topology aimed at enhancing system responsiveness under various conditions, including variable input voltages, reference voltage changes, load fluctuations, integration with photovoltaics, and battery charging. This approach ensures improved stability and performance, addressing the dynamic challenges inherent in such systems. A comparative analysis was conducted on two distinct control topologies for the proposed TDDC system, namely proportional–integral (PI) and advanced OC. Simulink software was used to model and simulate the proposed system. The results demonstrate lower rising and settling times of the TDDC for the OC and PI implementations, respectively. Additionally, the system with the OC eliminates 20% of the overshoot, while the system with OC minimizes the output voltage oscillations from 13% to 2% compared to the PI system. The OC was integrated into the TDDC to enhance system stability and improve the control loops, particularly the third loop. These improvements make the TDDC with OC suitable for application to renewable energy systems, microgrids, telecommunication networks, and electric vehicles, where precise control and stability are essential.

Experimental validation of an analytical transient model for saturated boosting gain in DC–DC converters with variable duty cycle

This paper presents an innovative approach to characterize the boosting gain saturation phenomenon in DC–DC converters with variable duty cycles, a crucial component in energy management applications such as renewable energy systems and IoT devices. While existing literature predominantly relies on steady-state models to explain boosting gain behaviour, this study reveals discrepancies between theoretical predictions and experimental observations, particularly at high duty cycles. The research introduces an analytical model to accurately capture the boosting gain dynamics of a boost chopper converter, addressing the limitations of traditional steady-state analyses. Through experimental validation and numerical simulations using CAD tools, a significant boosting gain saturation of approximately 2.2 is empirically observed, highlighting the necessity for a transient model approach. By providing a comprehensive understanding of the boosting ratio constraints in practical boost converters, this work contributes to advancing the analytical modelling techniques in the field. The mathematical model’s validation through rigorous experimental measurements and simulation analyses underscores its reliability and applicability in real-world scenarios. The structured organization of the paper elucidates the development and verification process, culminating in insightful conclusions that underscore the significance of transient modelling in enhancing the performance and efficiency of DC–DC converters.

Composite Switched Lyapunov Function-Based Control of DC–DC Converters for Renewable Energy Applications

Renewable energy sources play a pivotal role in the pursuit of sustainable and eco-friendly power solutions. While offering environmental benefits, they present inherent challenges. Photovoltaic systems rely on surrounding conditions, wind systems contend with variable wind speeds, and fuel cells are both costly and inefficient. Furthermore, the energy injected by renewable energy sources (RES) exhibits unpredictable behavior. To tackle these problems, researchers employ diverse power electronic devices and converters like inverters, power quality filters, and DC–DC choppers. Among these, DC–DC converters stand out for effectively regulating DC voltage and enhancing the efficiency of RESs. The meticulous selection of a suitable DC–DC converter, coupled with the integration of an efficient control technique, significantly influences overall power system performance. This paper introduces a novel approach to the design of switching controllers for DC–DC converters, specifically tailored for application in renewable energy systems. The proposed controller leverages the power of composite switched Lyapunov functions (CSLF) to enhance the efficiency and performance of DC–DC converters, addressing the unique challenges posed by renewable energy sources. Through comprehensive analysis and simulation, this study demonstrates the efficacy of the controller in optimizing power transfer, improving stability, and ensuring reliable operation in diverse renewable energy environments. Moreover, the small-scale DC–DC converter experiment’s findings are presented to confirm and validate the proposed scheme’s practical applicability.

Application of Delta PLC on Battery Management System in AC/DC Microgrid

To keep the energy balance and power quality in check, a proper controller must be made for all the parts of the microgrid to work together. The sizing of the microgrid is done by considering the distributed generators and their connected ACDC loads. The performance of DC will obtain according to the state of charge condition of the battery bank. So it is essential to operate the battery bank by observing the state of the charge condition. To maintain the voltage stability of the system the PLC (programmable logic controller) best switching controller is designed to operate the battery bank according to the distributed generators’ demand. The main objective of the present work is to enhance the power conversion efficiency and maintain voltage stability during essential conditions which are fulfilled by the Battery storage and its controller. It must provide effective voltage support in a fault condition.

Efficiency Optimization in Multi-Branch Converters through Dynamic Control

As the global emphasis on solar energy intensifies, optimizing the efficiency of photovoltaic panels becomes crucial in meeting energy demands sustainably. Addressing this, our research delves deeply into advancing maximum power point tracking (MPPT), a pivotal component in perfecting the energy conversion process. Leveraging state-of-the-art mathematical modeling, in-depth simulations, and comprehensive experimental validation, we set out to markedly refine the performance of non-isolated multi-branch buck DC–DC converters. In this pursuit, we introduce an innovative algorithm meticulously designed to adjust the number of active branches. This adjustment is rooted in robust efficiency metrics, ensuring optimal power delivery even under dynamic and fluctuating conditions. We place a distinct emphasis on the transformative role of current in determining converter efficiency. Drawing from our findings, we advocate for an adaptive control strategy, precisely engineered to thrive in a spectrum of operational contexts. With this study, we not only present pivotal contributions to the domain of photovoltaic technology but also chart out clear expectations for future endeavors. Our hope is that these advancements serve as foundational steps, guiding the evolution of sustainable energy generation.

Genetic-Algorithm-Driven Parameter Optimization of Three Representative DAB Controllers for Voltage Stability

In the process of integrating renewable energy sources into DC microgrids, the isolated bidirectional bridge plays a crucial role. Under load disturbances, voltage fluctuations in the microgrid can affect system stability. This study focuses on using a Genetic Algorithm to optimize the parameters of three typical DAB controllers (PI controller based on pole placement, sliding mode controller, and model predictive controller) with the aim of improving voltage stability, especially during sudden load drops. The results demonstrate that controllers optimized using Genetic Algorithm outperform the methods of pole placement and traditional manual tuning significantly. For the PI controller, the maximum drop rate reduced from 8.00% to 4.00%. The phase margin increased from 123° to 126°. In the case of the sliding mode controller, the maximum drop rate decreased from 7.50% to 5.00%. The phase margin increased from 127° to 155°. As for the model predictive controller, the maximum drop rate reduced from 1.00% to 0.70%. The gain margin increased from 25.8 dB to 26.2 dB. These results highlight the potential of using the Genetic Algorithm in optimizing control parameters, offering the prospect of improving the performance and stability of DC–DC converters.

Effective battery charging system using step voltage and step duty size-based MPPT controller for solar PV system

Solar energy is an excellent source of renewable energy, despite its intermittent nature that can pose a challenge. To meet load demand, a converter is required to integrate the system. The converter acts based on control signals from the controller, which is trained according to the end demand and availability of Sun Irradiance. This paper utilizes the Incremental Conductance (IC) and Perturb and Observe (P&O) algorithms, which are widely accepted in the industry and easy to implement. This study aims to design and compare a Step Voltage (SV) controller and a Step-Duty (SD) Maximum Point Tracking (MPPT) IC controller-based DC to DC boost converter. The paper compares the performance of SV and SD controller-based DC to DC boost converters under different environmental conditions, evaluates the system’s effectiveness by comparing the oscillations in load power for both conditions and discusses the impact of battery charging on the Load. The system performance is tested using MATLAB Simulink/coding, considering the Indian solar radiation intensity (SRI) scenario and temperature variations. Overall, this study provides a comprehensive analysis of the performance of the proposed system, which can contribute to the development and optimization of solar energy systems in various applications. From the comparative analysis of IC SD, SV and P&O SD, SV it is observed the performance of IC SD is superior. The impact of battery charging using IC SD controller on the load and MPPT point is also discussed.

Design and analysis of reconfigurable sensorless brushless DC motor drive for regenerative braking and battery charging in electric vehicle

SummaryThe expected depletion of fossil fuels has brought in an increased demand for electric vehicles with better performance in terms of easiness of control and reliability of operation and hence is a fertile area of research. In the present scenario, motoring, regenerative braking, and charging operations are performed in electric vehicles by separate converters. In this paper, an integrated scheme is developed, wherein the same voltage source inverter is employed to obtain all the three modes of operation, which in turn reduces the number of switching devices. Further, a sensorless control used in the proposed scheme improves the operational reliability. This novel approach adopts a simple switching scheme for voltage source inverter to operate as a dual‐boost DC‐DC converter during the regenerative braking period. This switching scheme enables reconfiguring voltage source inverter to a dual‐boost rectifier in conjunction with a LLC resonant converter in the charging mode. A comparison is also provided between the performance of single switch boost and dual‐boost converters used for braking operation. The performance of a prototype brushless DC (BLDC) motor drive with Li‐ion battery pack is evaluated in motoring, regenerative braking, and battery charging modes. This paper presents a detailed design of the scheme, the simulation of which is done on a MATLAB/SIMULINK platform and validated experimentally.

Enhancing Dynamic Stability Performance of Hybrid AC/DC Power Grids Using a New Robust Controller

This research investigates the dynamic performance of a multi-terminal DC (MTDC) network linked to a wind farm side converter. The suggested approach is based on loop shaping, mutual quality decomposition, and an effective H controller architecture (MQDM). The transfer function was built as the wind power plant shifted from the Master-Slave control approach to the conventional feedback control method. The singular value curves of the original open-loop system and the suggested solution are compared in order to derive the weighting functions of the robust H controller. The control gain is then calculated by utilizing the MQDM approach to get the system's transfer function from the state space. By using the single value order reduction approach and frequency response analysis to generate a robust controller's gain, the suggested methodology was put into practice. The suggested method for controlling the DC grid voltage on the MTDC converter on the wind farm side has now been implemented in the MATLAB environment. Applying various uncertainties to the DC grid, wind turbines, and AC grid using simulation data demonstrates how reliable the suggested approach is.

Investigation of Nonlinear PI Multi-loop Control Strategy for Aircraft HVDC Generator System with Wound Rotor Synchronous Machine

In order to enhance the transient performance of aircraft high voltage DC (HVDC) generation system with wound rotor synchronous machine (WRSM) under a wide speed range, the nonlinear PI multi-loop control strategy is proposed in this paper. Traditional voltage control method is hard to achieve the dynamic performance requirements of the HVDC generation system under a wide speed range, so the nonlinear PI parameter adjustment, load current feedback and speed feedback are added to the voltage and excitation current double loop control. The transfer function of the HVDC generation system is derived, and the relationship between speed, load current and PI parameters is obtained. The PI parameters corresponding to the load at certain speed are used to shorten the adjusting time when the load suddenly changes. The dynamic responses in transient processes are analyzed by experiment. The results illustrate that the WRSM HVDC generator system with this method has better dynamic performance.

Star Power Factor Correction Architecture

Conventional two-stage power factor correction (PFC) architecture based on a boost PFC front end and an isolated dc–dc back end is increasingly challenged by the recent trend toward higher power density and efficiency. One key reason for the challenge is the difficulty of increasing the operating frequency of the boost PFC stage. This article presents a new star PFC architecture that allows the boost PFC stage to operate efficiently at a higher frequency while maintaining the performance of the second dc–dc stage, leading to a high-power-density and high-efficiency ac–dc converter design across a universal input. The high performance of star architecture is enabled by realizing: 1) continuous-conduction-mode (CCM) operation of the boost PFC stage; and 2) full-range zero-voltage-switching (ZVS) of all active switches. In addition, the star architecture can: 1) operate at a constant frequency via a proper selection of the circuit topology and modulation method; and 2) be controlled based on simple and low-cost analog circuits. A 300-kHz, 240-W, 48-V-output, and universal-input prototype is built to verify the performance of the star architecture, showcasing high power factor, constant output voltage, 97.1 % full-load efficiency, 55.6 W/in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{3}$</tex-math></inline-formula> power density by box volume.

A hybrid scheme for optimal performance of photovoltaic system converters with multilayer structure

The interface of photovoltaic (PV) systems to the grid requires an efficient control strategy to operate, control, and improve power quality. The output voltage of the solar array, which may be accompanied by significant voltage variations, must be controlled and converted to a higher voltage for grid connection applications of photovoltaic system by a DC-DC converter that commands more attention. Recently, due to the increasing use of renewable sources, multilayer structure with different structures and designs to provide power and stability has been researched because the output voltage of solar arrays is usually low, so it is increasing to DC-to-DC converters, needed with optimal interest and efficiency. In this paper, a method to improve the performance of DC–DC converter used in PV system by using a combined design of forward and fly-back is presented. Due to the fact that isolated converters, flyback, and forward converters have a simple structure and are easy to control, but this converter is affected by high stress voltage. Therefore, this converter cannot be used for high power applications. To solve this problem, it has been improved in the proposed converter with the overlay and triple induction technique, which is a very good improvement on the voltage gain parameters in the short duty cycle. The voltage drop across the semiconductor switch is reduced. The investigations performed that the proposed DC/DC converter in Simulink MATLAB has been simulated. The results show that the suggested converter has an ideal efficiency of roughly 82.86% and provided higher voltage gain, decreased voltage stress, and reduced voltage jumps caused by disconnection.

Implementation of higher order sliding mode control of DC–DC buck converter fed permanent magnet DC motor with improved performance

ABSTRACT In this paper, an attempt is made to improve the performance of permanent magnet DC (PMDC) motor using third order sliding mode control. From the derived mathematical modelling for buck converter fed permanent magnet DC motor, expressions for both classical sliding surface (CSS) and proportional integral derivative sliding surface (PIDSS) with the third order sliding mode control is derived and compared analytically. Simulation work is done for PI controller, sliding mode control (SMC), third order CSS and third order PIDSS by using Matlab/Simulink to validate the performance of the above said controllers under no-load condition and various load torque conditions such as: constant load torque, frictional load torque, fan type load torque, propeller type load torque and undefined load torque. Experimental results are obtained with PMDC motor to validate the proposed control method for various speeds with different constant load torque conditions. Comparisons are carried out both in simulation and real time for PI controller, SMC, CSS and PIDSS based on the speed settling time and steady state error. Satisfactory results are obtained and presented in this paper.

A Commutation Optimization Strategy for High-Speed Brushless DC Drives With Voltage Source Inverter

The control performance of Hall sensor-based high-speed brushless dc (BLdc) motor drives depends heavily on the accuracy of Hall sensor signals. Due to the existence of Hall signal errors, the system may operate under unbalanced conditions that will lead to asymmetric currents and high-torque ripple. For high-speed BLdc drive, using voltage source inverter (VSI) with the pulsewidth modulation (PWM) technique will also lead to PWM update delay that causes inaccurate commutation. In this article, two Hall signal errors, i.e., misaligned and uneven Hall signal errors, are investigated and a Hall signal balancing strategy is developed to detect Hall signal errors and regenerate balanced Hall signals. A novel PWM generation scheme is then proposed to eliminate the PWM update delay when using traditional VSI. Both simulation and experiment results have verified the effectiveness of the proposed strategy.

An Input-Oriented Power Sharing Control Scheme With Fast-Dynamic Response for ISOP DAB DC–DC Converter

With some advantages, such as electric isolation, high efficiency, and fast dynamic response, the input-series output-parallel (ISOP) dual-active-bridge (DAB) dc–dc converter has been regarded as one of the most promising candidates for connecting the medium voltage terminal and the low voltage terminal. For the ISOP DAB dc–dc converter, the existing control strategies are mainly focusing on the equivalent power sharing control, but the fast-dynamic response is not included and the decoupling between the regulation of input voltage and the adjustment of output voltage is not eliminated significantly. In this article, the average model of this ISOP DAB dc–dc converter is presented first, which can be employed to analyze the power distributions of this modular topology clearly. Then, an input-oriented power sharing control scheme with fast-dynamic response is proposed for ensuring both the power sharing ability and the fast-dynamic performance of the ISOP DAB dc–dc converter in this article. Compared with the existing methods, this proposed scheme can also significantly reduce the coupling between the power sharing control and the output voltage regulation. In addition, an inductance-estimating method is proposed for ensuring the power sharing performance of the ISOP DAB dc–dc converter. Finally, the experimental results are provided to verify the effectiveness of the proposed input-oriented power sharing control with fast-dynamic response for the ISOP DAB dc–dc converter system.

A Comprehensive Comparison of Two Fast-Dynamic Control Structures for the DAB DC–DC Converter

Benefitting from some significant advantages, the dual active bridge (DAB) dc–dc converter has become one of the most promising candidates for dc–dc power conversion. In recent years, some strategies have been proposed to boost the dynamic performance of DAB dc–dc converter under the disturbance of input voltage and load condition. According to the relationship between the compensation part and the model-based part, these existing schemes can be divided into two structures including the parallel structure and series structure. In the parallel control structure, the compensation part is added to the model-based part. In contrast, the compensation part is multiplied with the model-based part in the series control structure. By adopting proper feedback control, both control structures can provide excellent dynamic performance for DAB dc–dc converter easily. Hence, the modified parallel-structure fast-dynamic control scheme and the modified series-structure fast-dynamic control scheme are both proposed in this article. Then, using these two proposed schemes as examples, the merits and the demerits of both structures are analyzed, and the corresponding compensation methods are also presented. Moreover, a general PI design principle of the model-based control scheme for the DAB dc–dc converter is provided, which is different from the traditional concept for designing the PI parameters. In addition, the control delay of these two proposed schemes is analyzed, and a compensation method is also proposed. Finally, simulation results and experimental results are obtained to verify the analysis in this article and the excellent performance of the proposed methods.

A Load-Current-Estimating Scheme With Delay Compensation for the Dual-Active-Bridge DC–DC Converter

The dual-active-bridge (DAB) dc&#x2013;dc converter is a promising candidate for the isolated dc&#x2013;dc power transferred applications, such as in the dc distribution system, the solid-state transformer, and the energy storage system. In these applications, the fast-dynamic response is usually a core requirement, especially under load changes. To improve the dynamic performance of the DAB dc&#x2013;dc converter, this article proposes a simple load-current-estimating (LCE) scheme with delay compensation for fast dynamic performance. Based on the current flowing model of the DAB dc&#x2013;dc converter, the LCE strategy is proposed with single-phase-shift modulation method. Moreover, the inherent switching-period delay phenomenon of the LCE scheme is analyzed. Therefore, the corresponding delay compensation method is proposed for further boosting dynamic responses, and the dynamic limitation of the LCE scheme may be obtained for DAB dc&#x2013;dc converter. Then, for the proposed LCE scheme, a damping coefficient is introduced to restrict the potential instability caused by the measurement noise, and the fast-dynamic response will be influenced a little when the load resistor is changed. In addition, the extended rule for the optimized triple-phase-shift modulation method is discussed. Finally, the simulation result and the experimental result both validate the fast-dynamic performance of this proposed LCE strategy without or with delay compensation.

Experimental Investigation of Performance, Reliability, and Cycle Endurance of Nonvolatile DC–67 GHz Phase-Change RF Switches

This article reports high-performance and reliable phase change material (PCM) germanium telluride (GeTe)-based nonvolatile radio frequency (RF) switches. The highly miniaturized ultrawideband dc to 67 GHz millimeter-wave (mmWave) switches is developed in-house using a custom eight-layer microfabrication process. The switches are fully passivated and do not require any special packaging for integrating heterogeneously with other technologies. They are also amenable to monolithic integration with a wide range of RF devices on a single chip, such as phase shifters, impedance tuners, and attenuators, to name a few. The PCM GeTe-based RF switches are experimentally tested for their RF performance variation across the wafer, performance change at high temperature, high-power handling capability, third-order intercept (TOI) through the two-tone testing setup, and switching speed. The nonvolatile resistance state reliability of the PCM switches is experimentally investigated. The presented RF switches are cycled more than one million times, demonstrating reliable actuation operation with a figure of merit exceeding 14.5 THz. A detailed description of the experimental setup for measuring the switching speed, power handling capability, linearity, reliability, and cycle endurance assessment of the PCM switches is presented. The PCM switches developed are compared with the current state-of-the-art demonstrating a clear improvement in various aspects of the switch’s performance.

Series-Parallel Reconfigurable Electric Double-Layer Capacitor Module with Cell Equalization Capability, High Energy Utilization Ratio, and Good Modularity

Voltages of electric double-layer capacitor (EDLC) modules vary rather wider than traditional secondary batteries. Although EDLCs should desirably be cycled in a voltage range as wide as possible to achieve a high energy utilization ratio, the wide voltage variation of EDLC modules impairs the performance of DC–DC converters. To address such issues, previous works reported series-parallel reconfiguration techniques, which are roughly divided into balance- and unbalance-shift circuits. However, conventional balance-shift circuits are not applicable to modules comprising odd number cells, impairing modularity. Unbalance-shift circuits, on the other hand, unavoidably cause cell voltage imbalance that reduces energy utilization ratio. This paper proposes a novel series-parallel reconfigurable EDLC module with cell voltage equalization capability. The proposed reconfigurable EDLC module is applicable to any number of cells, realizing good modularity. Furthermore, all cells in the proposed module can be charged and discharged uniformly without generating cell voltage imbalance, achieving an improved energy utilization ratio compared with conventional techniques. A five-cell module prototype was built for experimental verification. While the module voltage varied between 1.04 and 2.83 V, all cells discharged from 2.5 to 0.3 V. The result is equivalent to a 98.6% energy utilization ratio.